Semiconductor device manufacturers are migrating toward the use of high dielectric constant (e.g., high-k) gate dielectric, instead of the commonly used gate oxide. Metal gates, instead of polysilicon gates, are typically used to obtain the maximum benefit of using a high-k gate dielectric since a metal gate permits a better optimization of the work function between the gate, gate dielectric, and substrate. Many integration schemes use a damascene replacement gate process to form such metal gates.
For example, a damascene gate is commonly formed by first depositing a high-k gate dielectric on a substrate, depositing polysilicon on the gate dielectric, and patterning the polysilicon into a dummy gate (e.g., mandrel). Any desired spacers, implants (e.g., source, drain, halo, etc.), silicides, etc., are formed before an interlevel dielectric layer (ILD) is formed over the top of the structure. The ILD is then recessed down to the top of the polysilicon and the polysilicon dummy gate is stripped away, leaving a gate trench in the ILD. Metal is then deposited into the gate trench, resulting in a metal gate formed on a high-k gate dielectric.
Local interconnects are known in the industry for providing electrical connections to one or more gates. Local interconnects typically consist of a metalized wire formed in an ILD level above the ILD level of the gate, and vertical metal connections formed between the wire and the gate. Owing to this geometry, conventional local interconnects, or other wiring techniques through traditional wiring channels, have a relatively long circuit path and occupy a large amount of area within an integrated circuit (IC). Moreover, because conventional local interconnects are formed in additional wiring levels after the gates are formed, the formation of such local interconnects adds numerous processing steps to the semiconductor device fabrication. The additional processing steps necessarily increase the time and cost of fabrication.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.